The disclosure of Japanese Patent Application No. HEI 11-237918 filed on Aug. 25, 1999 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to an abnormality detection apparatus for a power supply circuit associated with a control apparatus for an internal combustion engine. More particularly, the invention relates to an abnormality detection apparatus that detects an abnormality in a power supply circuit having, as a power supply, a chargeable/dischargeable battery connected to a power generator and a load, and an internal combustion engine control apparatus that performs automatic stop/start control of an engine installed in a vehicle, that is, stops the engine when a predetermined condition is met, and restarts the engine when the condition is unmet after being met.
2. Description of the Related Art
An automatic stop/start control apparatus for an internal combustion engine is proposed (in, e.g., Japanese Utility Model Application Laid-Open No. SHO 63-65833) which has a battery sensor for detecting an abnormality of a battery. When the battery sensor detects an abnormality of the battery, the apparatus prohibits the automatic stop/start control of the internal combustion engine so as to prevent an automatic stop of the operation of the engine.
In some cases, however, this type of control apparatus fails to automatically restart the internal combustion engine. For example, if there is a contact failure in a power supply circuit that includes the battery, electric power is not supplied to a self-starting motor for starting the internal combustion engine even though the battery sensor does not detect an abnormality of the battery. Therefore, once the engine is automatically stopped with such an undetected power supply circuit failure, the engine cannot be automatically restarted.
Accordingly, it is an object of the power supply circuit abnormality detection apparatus of the invention to detect an abnormality that may occur in a power supply circuit and to direct the control of the automatic stop and the automatic start of an internal combustion engine with an internal combustion engine control apparatus, based on the state of a power supply circuit.
To achieve the aforementioned and other objects, one aspect of the invention provides an abnormality detection apparatus for a power supply circuit having a chargeable battery connected to a generator, the apparatus including a controller. The controller determines a state of the generator, determines a state of the battery, and determines that the power supply circuit is normal, (a) when the generator is in a generating state (where the generator is able to charge the battery) and the battery is in a charged state, or (b) when the generator is in a non-generating state and the battery is in a discharged state.
According to the above-described aspect, it is possible to determine whether the power supply circuit has an abnormality based on a combination of the state of the generator and the state of charge/discharge of the battery.
In the above-described aspect, the abnormality detection apparatus may further include a current detector that detects a current through the battery, wherein the controller detects an electric potential of at least a portion of a wiring connecting between the generator and at least one of the generator and a load, and wherein the controller detects an abnormality of the power supply circuit based on the electric potential detected and the current detected by the current detector. Therefore, it becomes possible to detect an abnormality including an abnormality related to an electrical connection. It also becomes possible to detect whether the battery is reversely connected and whether the engine is started by jump start.
Another aspect of the invention provides an abnormality detection apparatus for a power supply circuit of an internal combustion engine installed in a vehicle, the apparatus including an abnormality detection apparatus for a power supply circuit as described above and an engine controller. The engine controller automatically stops the internal combustion engine when a predetermined condition is met. The engine controller restarts the internal combustion engine when the predetermined condition is unmet after being met. When the abnormality detection apparatus determines that the power supply circuit has an abnormality, an automatic stop/start of the internal combustion engine is prohibited.
Therefore, when an abnormality is detected in the power supply circuit, the abnormality detection apparatus does not permit the automatic stop/start control apparatus of the internal combustion engine to stop/start the engine. Hence, the apparatus avoids an inconvenience where the engine cannot be automatically restarted.